Hi, Congratulations on coming over to the light side! Honestly, nobody knows exactly how much nicotine we're getting, but we never really knew before either. All we know for sure is that we're getting zero carbon monoxide, formaldehyde and a thousand+ other nasty things.
I, too, vape almost constantly sometimes. If you are getting too much nicotine into your bloodstream too quickly you will become nauseous. You probably know that Nicotine is a stimulant in small amounts, but a poison if you have too much. Fortunately, Mother nature saves you by making you throw up before you can do any serious harm.
I know this not only because I made myself self queasy a few times when I started, but also because I went through an aversion therapy at the "Schick Center for the Control of Smoking" back in the '70's. (Schick does rehab now, I think) It consisted of paying a lot of money to smoke until you barfed. It had a dismal success rate, but they never killed anybody by nicotine overdose. So, I don't think it needs to be a worry. If you feel okay, not jittery or otherwise "off", you're not overdoing it. Some people fail at this when they continue to crave cigarettes because that are not getting enough nic through vaping to feel satisfied.
Once you feel like you know what you're doing, it's not hard to start mixing your own liquids, making it easier to find the right amount for you.